Process and compositions for stabilizing the thermal generation of pesticidal fogs



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' PROCESS AND COMPOSITIONS FOR STABHJZENG ample, in the TIFA insecticidal fog applicator (made by vTodd Shipyards Corporation), one of the most widely used generators of the thermal aerosol type, air is pumped to a combustion chamber where it is raised to a temperature of about 950 to 1050 F. The hot gas stream is pumped, at a pressure of about 40 to about 70 pounds p.s.i.g., to an atomizer cup. The liquid to be fogged is introduced to the atomizer cup at lower pressure, e.g.

about 25 p.s.i.g., and is atomized into a fine spray. The spray is dispersed as a fog by expansion through a nozzle.

Despite the extremely short residence time in the atomizer cup and fogging nozzle, the severe high temperature conditions result in very rapid carbon formation. It is often necessary to clean out the atomizer cup and nozzle every few hours under continuous operating conditions. The resulting down-time is a major cost factor in fogging operations since complete dismantling of the nozzle assembly is necessary for cleaning. Thisis troublesome on the job location because fogging operations are normally conducted in the very early morning am. to 8 am.) or the late evening (7 pm. to midnight) when it is usually dark and because fogging operations are usually conducted in locations remote from maintainence facilities. Moreover, after about an hour of fogging before complete stoppage, carbon deposition interferes with fogging efiiciency to an extent creating a serious problem in the field.

Experiments have been made varying the-oil carrier for the insecticidal solution or emulsion in an effort to reduce carbon deposition. Although the use of highly refined lightoils such as kerosenes in place of the usual heater and furnace oils has efiected some improvement, the basic problem remains because of the inherent instability of most oils and other organic components of the fogging compositions under the extreme conditions of temperature and pressure change encountered in thermal fogging operations. We have found, however, that carbon formation in the generation of pesticidal fogs can be substantially eliminated by including a stabilizer in the material to be fogged. The stabilizer'of our invention is a detergent-dispersant of the type commonly employed This is a preferentially oil soluble metal soap of a structure including a strongly polar group coupling the metal with a high molecular weight hydrocarbon group, preferably containing a long chain. The most suitable detergent-dispersant known to us for use as a fogging stabilizer is a metal soap of a phospho-sulfurized reaction product of a hydrocarbon of sufficient molecular weight to impart preferential oil solubility to the detergent structure. For example, a potassium or barium neutralized reaction product of phosphorus sulfide and an olefin polymer, advantageously a polybutene fraction of about 450 to 500 molecular weight, has special value. Materials of this sort are described in US. Patents 2,316,080, 2,316,082 and 2,377,955. We have found that combination of a detergent of this type with a polyamine such as a long chain, N-alkyl propylene diamine or or-, garlic salt thereof has special advantage in providing long continuous periods of fogging operation free from shutdown caused by carbon deposition and nozzle clogging. in the practice of the invention, the stabilizer is usually incorporated in the pesticidal or insecticidal composition which is to be fogged. In general, the insecticidal com-- position is formulated as a concentrate of the selected insecticide, e.g. DDT, in an oil carrier for economy in shipping and handling. Before fogging, the concentrate.

is cut-back with oil to the specified insecticidal concentration, e.g. about 5 to 8 percent for DDT. The concentration of insecticide must be selected in accordance with the level of eifective concentration of the particular insecticide for the particular pest or insect to be controlled. The stabilizer of the invention is usually made up in the form of an oil concentrate, for example, a concentrate containing 10 to 50 percent of the oil-free, active components in a light cycle oil, boiling in the range of 450 to 750 l-a, of the type derived from petroleum cracking operations.

The formulation also included 3 percent Triton X-100, anv

alkylatedaryl polyethylene oxide condensation product, as an emulsifying agent and 1.5 percent calcium mahogany soap, anoil soluble petroleum sulfonate. This composition Was cut back to 5 percent DDT with a furnace oil comprising a mixture of 60 percent virgin gas oil distillate and 40 percent catalytic cycle oil boiling in the range 300 to 650 F. and which contained 0.01 percent of an additive mixture comprising 0.004 percent of Ntal-' low propylene diamine (Duomeen T), 0001 percent of N-tallow propylene diamine oleate and 0.005 percent of a potassium neutralized reaction product of phosphorus pentasulfide and butene polymersummer.

'The stabilized composition was tested for the control of mosquitos and flies by foggingwith a TIFA insecticidal fogging generator in operations extending over an entire that using on the averageof 500 gallons per week not one minute of down time was required for cleaning. Two units wereoperated during the period without taking the oil or range oil. Thus, the major cause of lost time in conducting thermal fogging operations was eliminated while percent efficiency at the fogging nozzle was assured.

In greater detail, the detergent-dispersant of the invention may be obtained by reacting a phosphorus sulfide with a hydrocarbon at a temperature of from about 200 Patented June 19, 1962;

The stabilizer concentrate then can be' added to the insecticidal concentrate 0r to the cut-back The operator of thetest equipment reported' P. to about 600 F., and preferably from about 250 F. to about 500 F., using from about 1 percent to about 50 percent, and preferably from about percent to about 25 percent by weight, of the phosphorus sulfide in the reaction. It is advantageous to maintain a non-oxidizing atmosphere, such as for example, an atmosphere of nitrogen above the reaction mixture. Usually, it is preferable to use an amount of the phosphorus sulfide that will completely react with the hydrocarbon so that no further purification becomes necessary;however, an excess of phosphorus sulfide can be used and separated from the product by filtration or by dilution with a solvent, such as hexane, filtering and subsequently removing the solvent by suit able means, such as by distillation. The phosphorus sulfide-hydrocarbon reaction products contain both sulfur and phosphorus. The reaction may if desired be carried out in the presence of an additional sulfurizing agent or the phosphorus sulfide-hydrocarbon reaction product can be sulfurized, as described in U.S. 2,316,087 issued April 6, 1943, to James W. Gaynor and Clarence M. Loane.

The hydrocarbon constituent of the reaction is preferably a mono-olefin hydrocarbon polymer resulting from the polymerization of low molecular weight mono-olefinic hydrocarbons or isomono-olefinic hydrocarbons, such as propylene, butylenes, and amylenes or the copolymers obtained by the polymerization of hydrocarbon mixtures containing isomono-olefins and mono-olefins or mixtures of olefins in the presence of a catalyst, such as sulfuric acid, phosphoric acid, boron fluoride, aluminum chloride or other similar halide catalysts of the Friedel-Crafts type.

The polymers employed are preferably mono-olefin polymers or mixtures of mono-olefin polymers and isornono-olefin polymers having molecular weights ranging from about 150 to about 50,000 or more, and preferably from about 300 to about 10,000. Such polymers can be obtained, for example, by the polymerization in the liquid phase of a hydrocarbon mixture containing mono-olefins and isomono-olefins such as 'butylene and isobutylene at a temperature of from about 80 F. to about 100 F. in the presence of a metal halide catalyst of the Friedel- Crafts types such as, for example, boron fluoride, aluminum chloride, and the like. In the preparation of these polymers there may be employed, for example, a hydrocarbon mixture containing isobutylene, butylenes and butanes recovered from petroleum gases, especially those gases produced in the cracking of petroleum oils in the manufacture of gasoline. US. 2,407,873 to Evering et :11. describes a particularly suitable technique for polymerizing such olefins in the presence of an aluminum-chloridehydrocarbon complex catalyst.

Essentially parafiinic hydrocarbons such as bright stock residuums, lubricating oil distillates, petrolatums or parafiin Waxes may be used. The condensation products of any of the foregoing hydrocarbons or their halogen derivatives, with aromatic hydrocarbons can also be em.- ployed.

Examples of high molecular weight olefinic hydrocarbons which can be employed as reactants are cetene (C cerotene (C melene (C and mixed high molecular Weight alkenes obtained by cracking petroleum oils. Other olefins suitable for the preparation of the herein described phosphorus sulfide reaction products are olefins having at least 20 carbon atoms in the molecule of which from about 12 carbon atoms to about 18 carbon atoms, and preferably at least carbon atoms, are in a long chain. Such olefins can be obtained by the de-.

hydrogenation of paraiiins, such as by the cracking of paraffin waxes, or by the dehalogenation of alkyl halides, preferably long chain alkyl halides, particularly halo gcnated parafiin Waxes. Also, olefins derived from the synthol of hydrocarbon syntheses process may be employed. These are essentially straight chain compounds varying widely in molecular weight.

Also contemplated within the scope of the present in- 4i vention are the reaction products of a phosphorus sulfide with aromatichydrocarbons such as benzene, naphthalene, anthraceneatoluene, diphenyl, etc. and alkylated aromatic hydrocarbons such as, for example, an alkyl benzene characterized by having at least one alkyl group of at least four carbon atoms, and preferably at least eight carbon atoms such as a long chain paraffin wax.

The phosphorus sulfide reactant can be any phosphorus sulfide, such as for example, P 5 P 3 and preferably P 8 The phosphorus sulfide hydrocarbon reaction product normally shows a titratable acidity which is neutralized by treatment with a basic reagent. The phosphorus-sulfide-hydrocarbon reaction product when neutralized with a basic reagent containing a metal constituent is characterized by the presence or retention of the metal constituent of the basic reagent. Other metal constituents such as a heavy metal constituent can be introduced into the neutralized product by reacting the same with a salt of the desired heavy metal.

The term neutralized phosphorus sulfide-hydrocarbon reaction product" as used herein means a phosphorus sulfide hydrocarbon reaction product having at least about 1 percent of its titratable acidity neutralized by the reaction with a basic reagent and includes the neutralized phosphorus sulfide-hydrocarbon reaction products containing a metal constituent resulting from said neutralization or resulting from the double decomposition of the phosphorus sulfide-hydrocarbon reaction product treated with a heavy metal salt.

The neutralized phosphorus sulfide-hydrocarbon reaction product can be obtained by treating the reaction 7 product with a suitable basic compound such as a hydroxide, carbonate, sulfide, or an oxide of an alkaline earth metal, e.g. calcium or barium, and preferably the latter, or an alkali metal such as, for example, potassium hydroxide or sodium hydroxide. The products are neutralized by mixing a suitable base (e.g. a 50 percent solution of KOH) therewith and heating to a temperature in the range of from about 200 to about 400 F. After the base and phosphorus sulfide-hydrocarbon reaction product are mixed they are preferably steamed at a temperature of about 400 F. for about a half hour. The steaming may take place during neutralization.

The useful detergents appear to be characterized in composition and structure by the presence of a metal, e.g. potassium, calcium, barium, magnesium, zinc, aluminum etc., coupled to an oil solubilizing group by the polar phosphorus and sulfur containing group.

The polyamine constituents, which are employed in a preferred by more specific aspect of the invention, are amines such as N-n-cetyl-propylene diamine, the various Duomeens (products of Armour Chemical Division) which have/the general formula RNHCH CH CH NH wherein R may be derived from coconut fatty acid (Duomeen C), from tallow fatty acid (Duomeen T), from lauric acid (Duomeen 12), or from soya fatty acid (Duomeen S), etc. The Duomeens are industrial or technical grade chemicals with an amine content of approximately calculated as di-amine. The approximate melting ranges for each of the aforementioned Duo- Ineens are: Doumeen C20 to 24 C., Duorneen 12-28 to 32 C., Duomeen S--38 to 42 C., and Duomeen T44 to 48 C.

The salts of the polyamines which also may be employed in accordance herewith may be prepared by reacting, under carefully controlled, non-dehydrating conditions, i.e. below about 200 F. and preferably below about F., a carboxylic acid containing from about 6 to about 20 carbon atoms, and preferably at least about 12 carbon atoms, e.g. hexanoic, nonanoic, lauric, stearic, oleic, linoleic, linolenic, palmitic, etc., with any of the described amines to obtain either the monoor di-substituted acid salts of the amines. Care must be taken in the preparation of such salts inasmuch as prolonged exposure to temperatures higher than about 200 F. results in the formation of amides ,or even 'glyoxalidines (if 1,2-substitutcd polyamines are employed) upon splitting out water. Among the very economical, commercially available salts of this type are the oleic acid monoand/or di-salts of the Duomeens (above described), particularly of Duomeen T. a

The stabilizersof the invention may be employed in variable proportions depending upon other components of the fogging composition. As little as OLOOS percent to as much as about 10 percent by weight may be desired. When the combination of detergent and amine are employed, about equal proportions are most suitable, but the amine may comprise as much asv about 90 percent of the combination.

Insecticidal compositions containing the stabilizers of the invention may Vary widely in composition because there are many pesticides and insecticides which are appropriately applied in this manner in large scale, insect and pest control operations. The compositions all employ an oil carrier for the insecticide although the oil concentrate can be cut-back with water to form an emulsion for fogging purposes. For this'purpose an emulsifying agent such as an alkyl aryl sulfonate, a polyglycol ester, a polyoxyethylene derivative, and the like should be used. The oil carrier and/or the cut-back solvent may be a light hydrocarbon distillate, advantageously as produced in petroleum distillation or petroleum cracking operations.

Usually a distillate of reasonably close out distillate is desired having a flash point above the gasoline range for safety. Thus, naphthas, kerosenes and gas oils boiling in the range of about 300 to 550 or 650 F., are suitable. Depending upon the insecticide, special solvents such as xylene rich or solvents or chlorinated solvents may be required or desirable. A number of typical formulations Potassium salt of P S -polybutene reaction prod- 6 Example V Percent Lindane 25.0 Emulsifying Agent 5.0 Aromatic solvent 69.835 Potassium salt of P S -polybutene reaction product 0.5 Duomeen T- 0.4 Duomeen T-nleate Example VI 4 Malathion 50.0 Emulsifying Agent 6.0 Aromatic solvent 43.67 Potassium salt of P S -po1ybutene reaction In the above examples, the mineral oil may be a keroproduct sene or light gas oil, and the aromatic solvent may be with advantage an aromatic solvent of the mixed alkyl benzenes or mixed alkyl naphthalenes types recoverable from catalytic hydroformates.

We claim:

1. In aprocess for control of insects and pests by generating pesticidal fogs from a fogging liquid comprising an oil-carried pesticidal composition by means of equipment for atomization of the fogging liquid at high temperature, the improvement which comprises using, as a stabilizer, an oil soluble metal soap of a phosphorus sulfide-high molecular. weight hydrocarbon reaction product in said fogging liquid in an amount effective to reduce formation of coke by thermal decomposition of the pesticide com position.

2. The process of claim 1 in which the stabilizer also contains an N-substituted alkyl propylene diamine in which the alkyl group contains from about 6 to about 30 carbon atoms.

3. The process of claim 1 in which the stabilizer i a potassium soap of a phosphorus pentasulfide-polybutene reaction product.

4. A stabilized composition for thermal generation of pesticidal fogs which comprises an oil carrier, an oil soluble pesticide suitable for fogging in an oil carrier medium and a stabilizer comprising a metal "salt of a phosphorgs sulfide-high molecular weight hydrocarbon reaction product in' an amount efiective to reduce carbon deposition thereof in thermal aerosol equipment.

5. The composition of claim 4 in which the stabilize is a metal salt of a phosphorus pentasulfide-polybutene reaction product.

6. The composition of claim 5 in which the stabilizer is a potassium salt of a phosphorus pentasulfide-polybutene are set out below.

2 Example I Percent DDT 25 Emulsifying agent 5 Aromatic solvent 69.7 Potassium salt of P S -polybutene reaction product 0.015 Duomeen T 0.012 Duomeen T-oleate 0.003

Example II DDT 25 Emulsifying agent 5 Aromatic solvent 69.985 Potassium salt of P S -polybutene reaction product 0.015

Example III Toxaphene- 60.0 Emulsifying agent 7.0 Mineral oil 32.0

uct 0.5 v Duomeen T 0.4 Duomeen T-oleate 0.1

Example IV Toxaphene 60.0 Emulsifying agent 7.0 Mineral oil 32.95 Potassium salt of P S -polybutetne reaction product I 0.05

References Cited in the file of this patent UNITED STATES PATENT S 2,316,080 Loane Apr. 6, 1943 2,316,082 Loane Apr. 6, 1943 2,316,088 Loane Apr. 6,1943 2,409,799 Roberts Oct. 22, 1946 2,684,292

Caron July 20, 1954 

1. IN A PROCESS FOR CONTROL OF INSECTS AND PESTS BY GENERATING PESTICIDAL FOGS FROM A FOGGING LIQUID COMPRISING AN OIL-CARRIED PESTICIDAL COMPOSITION BY MEANS OF EQUIPMENT FOR ATOMIZATION OF THE FOGGING LIQUID AT HIGH TEMPERATURE, THE IMPROVEMENT WHICH COMPRISES USING, AS A STABILIZER, AN OIL SOLUBLE METAL SOAP OF A PHOSPHORUS SULIFIDE-HIGH MOLECULAR WEIGHY HYDROCARBON REACTION PRODUCT IN SAID FOGGING LIQUID IN AN AMOUNT EFFECTIVE TO REDUCE FORMATION OF COKE BY THERMAL DECOMPOSITION OF THE PESTICIDE COMPOSITION.
 4. A STABILIZED COMPOSITION FOR THERMAL GENERATION OF PESTICIDAL FOGS WHICH COMPRISES AN OIL CARRIER, AN OIL SOLUBLE PESTICIDE SUITABLE FOR FOGGING IN AN OIL CARRIER MEDIUM AND A STABILIZER COMPRISING A METAL SALT OF A PHOSPHORUS SULFIDE-HIGH MOLECULAR WEIGHT HYDROCARBON REACTION PRODUCT IN AN AMOUNT EFFECTIVE TO REDUCE CARBON DEPOSITION THEREOF IN THERMAL AEROSOL EQUIPMENT. 